This proposal is concerned with the molecular mechanisms that regulate the synthesis and degradation of membrane lipids in bacteria. The metabolism of two vitamins, lipoic acid and biotin, that are related to fatty acids are also studied. The general approach is to use genetics, biochemistry, and molecular biology to unravel these mechanisms and determine how the pathways are regulated. The mechanisms of fatty acid metabolism are highly conserved throughout metabolism thus giving these studies general applicability. However, in the case of fatty acid synthesis the details of the pathways differ sufficiently that compound that specifically inhibit the bacterial enzymes have been found. Therefore, bacterial fatty acid synthetic enzymes are excellent targets for new antibiotics. It should be noted that a group of protozon parasites including the malarial parasite have essential fatty acid synthetic enzymes that are closely related to the bacterial proteins and thus new antibiotic should prove effective versus these parasitic diseases. [unreadable] [unreadable]